Pyrotechnic compositions containing epoxidized copolymers



United States Patent Oflice 3,490,967 Patented Jan. 20, 1970 3,490,967 PYROTECI-INIC COMPOSITIONS CONTAINING EPOXIDIZED COPOLYMERS Philip H. Rhodes and Paul L. Imes, Cincinnati, Ohio, assignors to Swift 8: Company, Chicago, Ill., a corporation of Illinois No Drawing. Filed Feb. 3, 1967, Ser. No. 613,769 Int. Cl. C06d 1/02 US. Cl. 149-19 10 Claims ABSTRACT OF THE DISCLOSURE A pyrotechnic composition containing a fuel, an oxi dizing agent and a binder component, wherein the binder comprises an epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymer.

This invention relates to new and improved pyrotechnic compositions. More particularly, it relates to solid pyrotechnic compositions consisting essentially of a pyrotechnic mixture and a binder, wherein the binder component comprises an epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymer.

The term pyrotechnic composition encompasses such pyrotechnic articles as illuminants, flares, fireworks and propellants. As normally composed, such pyrotechnic compositions consist essentially of a pyrotechnic mixture and a binder material. The pyrotechnic mixture is normally composed of a fuel-oxidizer system, that is, a mixture of a fuel and an oxidizing agent. The term fuel is a rather unscientific word which refers to substances which liberate heat during burning and which act as a chemical reducing agent, i.e., are themselves oxidized by the oxidizing agent. The fuel component of pyrotechnic mixtures may be either a metal or a non-metal and may be a native element or a compound. Some metals suitable for use as fuels aremagnesium, aluminum, potassium, barium, strontium, antimony, titanium, zirconium, iron,

manganese, zinc, nickel and the like, as well as certain alloys thereof. The most frequently used non-metals are sulfur, carbon, phosphorous, boron, silicon and the like. Sulfur, selenium and tellurium can be used as oxidizers as well as fuels. Oxidizers other than oxygen, sulfur, selenium and tellurium which may constitute the oxidizing agent component of pyrotechnic mixtures are the halogens, nitrogen, silicon and other well known oxidizing agents. These oxidizers may be in-their elemental form but are usually present as part of a compound.

The present invention is predicated on the discovery that epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymers can be employed to provide an improved binder component for pyrotechnic compositions. Known binder compositions have presented long standing problems which have not been solved heretofore. Many of the known binders require lengthy and complex processing to produce the required characteristics for satisfactory use in pyrotechnic compositions. Also, the introduction of extraneous impurities is often necessary in preparing these binders for pyrotechnic compositions. For example, curing agents and plasticizers are often required. These curing agents and plasticizers frequently interfere with uniform combustion of the pyrotechnic composition and also often give off toxic gases upon ignition.

Another problem that has been encountered with many of the known resinous binders is that they have certain characteristics which makes working with them difficult and sometimes hazardous. For example, some known resinous binders such as the glycidyl polyether binders produce brittle compositions which is undesirable because of the possibility that the binder will crack and produce fissures which increase the burning surface of the composition and consequently adversely affect the rate of gas evolution of the pyrotechniccomposition. Other known resinous binders such as the polyurethanes produce very rubbery compositions which are difiicult to work with. Many other known resinous binders are too rigid at low temperatures to be conveniently worked with and, therefore, must be heated to high temperatures in order to provide suflicient flexibility; however, this factor makes the use of these binders very dangerous When pyrotechnic compositions having a low ignition temperature are utilized.

It is, therefore, an object of this invention to provide a new and improved binder composition or pyrotechnic compositions which can be used in a more efficient and economical manner than has heretofore been possible.

It is another object of this invention to provide a new and improved binder composition for pyrotechnic compositions which requires no curing agent and is sufiiciently flexible and workable at low temperatures, Without plasticizers, to permit its use in pyrotechnic compositions having low ignition temperatures.

It is a further object of this invention to provide a new and improved binder composition which will provide solid pyrotechnic compositions which are not brittle and which can be cast into any predesigned geometrical shape of any convenient size.

It is a still further object of this invention to provide a new use of epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymers as binder components for pyrotechnic compositions.

Additional objects if not specifically set forth herein will be readily apparent to those skilled in the art from the following detailed description of the invention.

Generally, this invention comprises a novel, solid pyrotechnic composition employing a binder having the composite properties of flexibility, bond strength and uniform combustibility in admixture with a known fueloxidizer system. It consists of the fuel and oxidizer in admixture with an epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymer.

More specifically, the pyrotechnic compositions of the present invention can be prepared without harmful effect or ignition of the pyrotechnic mixtures by curing a mixture of an epoxidized higher fatty acid ester and a dior polybasic organic acid anhydride in the presence of a pyrotechnic mixture. When a solid anhydride is used it is sometimes preferred to melt the anhydride before mixing it with the epoxidized fatty acid ester and the pyrotechnic mixture. The temperatures at which this curing is carried out will vary depending on the particular copolymer binder which is being utilized; however, the curing temperatures of the binders of this invention are generally in the range of from about 60 C. to about C.

Mixtures of two or more organic dior polybasic acid anhydrides have the advantage over simple anhydrides of lower melting points. This makes it possible to add the molten anhydride at a lower temperature to the mixture.

Another variable factor in preparing the compositions of the present invention is the ratio of the amount of binder material to be used to the amount of pyrotechnic mixture present. This ratio can be varied within a 'broad range depending on the particular components employed and the physical characteristics of the desired final product. However, generally it is preferred that an amount of binding material in the range of from about 5% to about 35% by weight of the total pyrotechnic composition be employed, with a more preferred range of from about 15% to about 30% by weight of the composition.

As described above, the binder component of the compositions of the present invention comprises a copolymer prepared by reacting an epoxidized higher fatty acid ester with an organic acid anhydride. Suitable epoxy higher fatty acid esters which may be utilized as a constituent of the copolymer can be any of the well-known epoxidized vegetable oils, such as, for example, epoxidized linseed oil, exoxidized soybean oil, epoxidized safflower oil, epoxidized cottonseed oil, epoxidized perilla oil, epoxidized tall oil esters, and the like. It is generally preferred that the oxirane content of the epoxy ester constituents be as high as possible; therefore, the higher fatty acid esters employed should be substantially completely epoxidized. It is desirable that the fatty acid or mixture of fatty acids forming the fatty acyl portion of the ester have an oxirane content above about 8.8% and as a practical matter in the range of from about 8.8 to about 12.3%. The preferred oxirane content is from about 9 to about 10.5% for the fatty acyl Component.

A particularly desirable fatty acid mixture, which when epoxidized provides a very convenient source of the epoxy ester, is one containing less than about 35% epoxy linoleic acid and the total epoxy linoleic-epoxy linolenic acid content being above about 60%. This preferred mixture is readily obtainable from naturally-occurring linseed oil or perilla oil by subjecting such oils, provided they possess an iodine value above about 170, to an epoxidation treatment. It is also possible to obtain a high oxirane fatty acid ester mixture by treating fatty acids or fatty acid esters before epoxidation to remove as much of the saturated or mono-unsaturated fatty acids or esters as possible. Purified and concentrated fatty acid mixtures containing a large portion of unsaturated fatty acids can be obtained from vegetable oils, such as soybean oil and tall oil, etc.

The organic acid anhydride component of the epoxy ester-organic acid anhydride copolymers may be any of the well-known simple or mixed organic acid anhydrides of dior polybasic acids. Exemplary of suitable anhydrides are maleic anhydride, methyl nadic anhydride, dodecenyl succinic anhydride, phthalic anhydride, citraconic anhydride, ehlorendic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, endo-cis-bicyclo (2,2,1 heptene 2,3-dicarboxylic anhydride and the like.

The following examples are set forth for the purpose of illustration only and are not intended to be construed as being limitative in any respect.

EXAMPLE I A pyrotechnic mixture is prepared by mixing the following proportion of ingredients:

G. Atomized aluminum powder 20 Sodium nitrate powder 50 Sulfur powder 30 A binder mixture of the following proportion of ingredients:

Maleic anhydride 4.8 Methyl nadic anhydride W. 8.2 Epoxidized linseed oil (oxirane=9.0%) 24.0

technic composition, when ignited, burned rapidly With a brilliant flame.

EXAMPLE II By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients I EXAMPLE III By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients Pyrotechnic mixture: G. Atomized aluminum powder 25 Potassium chlorate 50 Sulfur 25 Binder mixture:

Maleic anhydride 3.6 Methyl nadic anhydride 6.1

- Epoxidized linseed oil (oxirane= 9%) 17.8

EXAMPLE IV By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients- Pyrotechnic mixture: G. Strontium nitrate 67 Potassium chlorate 33 Binder mixture:

Maleic anhydride 2.3 Dodecenyl succinic anhydride 2.2 Epoxidized linseed oil (oxirane=9%) 8.0

EXAMPLE V By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients Pyrotechnic mixture: G. Aluminum powder 41.7 Potassium chlorate 58.3

Binder mixture Maleic anhydride 4.6 Dodecenyl succinic anhydride 4.4 Epoxidized linseed oil (oxirane=9%) 16.0

EXAMPLE v1 By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients- Pyrotechnic mixture: G. Aluminum powder 28.6 Barium nitrate 57.2

Sulfur 14.2

Binder mixture:

Methyl nadic anhydride 6.5 Tetra hydrophthalic anhydride 5.4 Epoxidized linseed 'oil (oxirane=9%) 18.1

EXAMPLE VII By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients- Pyrotechnic mixture: G. Aluminum powder 35.6 Barium nitrate 21.7 Potassium chlorate 42.7

Binder mixture:

Methyl nadic anhydride 5.8 Tetra hydrophthalic anhydride 4.9 E-poxidized linseed oil (oxirane=9%) 16.3

EXAMPLE VIII By the procedure of Example I a pyrotechnic composition is prepared having the following proportions of ingredients Pyrotechnic mixture: G. Magnesium powder 8.3 Antimony trisulfide 8.3 Potassium nitrate 58.3 Sulfur 25.1

Binder mixture:

Phthalic anhydride 5.7 Dodecenyl succinic anhydride 10.3 Epoxidized linseed oil (oxirane=9%) 19.0

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. In a pyrotechnic composition containing a pyrotechnic mixture consisting essentially of a fuel-oxidizer system and a binder, the improvement comprising the use of a copolymer of an epoxidized higher fatty acid ester having an oxirane content above about 8.8% and a dior polybasic organic acid anhydride as the binder component.

2. The composition of claim 1 wherein the binder com- 10 ponent comprises 5% to 35% by weight of the composltlon.

3. The composition of claim 1 wherein the oxirane content of the epoxidized higher fatty acid ester constituent of the copolymer is between about 8.8 and about 4. The composition of claim 1 wherein the epoxy higher fatty acid ester-organic acid anhyride copolymer is an epoxidized vegetable oil-organic acid anhydride copolymer.

5. The composition of claim 1 wherein the epoxy higher fatty acid ester-organic acid anhydride copolymer is an epoxidized linseed oil-organic acid anhydride copolymer.

6. The method of using an epoxidized higher fatty acid ester-dior polybasic organic acid anhydride copolymer as a binder component in a pyrotechnic composition comprising: curing a mixture of an epoxidized higher fatty acid ester having an oxirane content above about 8.8%

and an organic acid anhydride in the presence of a pyrotechnic mixture.

7. The method of claim 6 wherein the curing temperat-ure is in a range of from about 60 C. to about 150 C.

8. The method of claim 6 wherein the amount of binder component incorporated in the pyrotechnic composition is in the range of from about 5 to about 35 by weight of the composition.

9. The method of claim 6 wherein the epoxy higher fatty acid ester-organic acid anhydride copolymer is an epoxidized vegetable oil-organic acid anhydride copolymer.

'10. The method of claim 6 wherein the epoxy higher fatty acid ester-organic acid anhydride copolymer is an epoxidized linseed oil-organic acid anhydride copolymer.

References Cited Military Explosives, TM91910, TO11A 1-34, Depts. of the Army and the Air Force, April 1965, pp. 274-283.

BENJAMIN R. PADGE'IT, Primary Examiner us. c1. X.R. 

